Spray cooled motor system

ABSTRACT

A spray cooled motor system with a motor housing with an interior and an exterior, a stator mounted within the interior of the motor housing, a rotor mounted within the interior of the motor housing, a coil winding mounted within the interior of the motor housing, a plurality of atomizers configured to spray a coolant on at least one of the stator and the rotor, a coolant pump in fluid communication with the plurality of atomizers; and an output shaft extending through an output shaft aperture from the interior to the exterior of the motor housing.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from U.S. ProvisionalApplication Serial No. 60/234,565 filed Sep. 22, 2000, titled“INTEGRATED MOTOR, THERMAL CONTROL AND POWER ELECTRONICS”, namingCharles L. Tilton as Inventor, and which is incorporated herein by thisreference.

TECHNICAL FIELD

[0002] This invention generally pertains to a spray cooled motor system.

BACKGROUND OF THE INVENTION

[0003] While motors have been known for years, their performance hasbeen limited by thermal constraints and their ability to remove heatfrom part or all of the motor. Improved thermal characteristics and/orenhanced motor operational characteristics may be achieved with internalspray cooling.

[0004] It is an object of this invention to provide a spray cooledelectric motor system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

[0006]FIG. 1 is a perspective view of a conceptual motor which includesan embodiment of a spray cooling system contemplated by this invention;

[0007]FIG. 2 is a conceptual cross-section of a rotor and one statorpole/winding which may be utilized in an embodiment of this invention;

[0008]FIG. 3 is an enlarged view of the stator pole/winding illustratedin FIG. 2;

[0009]FIG. 4 is a perspective end view of a nozzle ring manifold whichmay be utilized in an embodiment of this invention, showing 12 sets of 3nozzle orifices, which provides 3 spray orifices per winding gap;

[0010]FIG. 5 is a partial view of the spray assembly and positioning ofnozzle orifices relative to the stator pole/windings and rotorillustrated in FIG. 2;

[0011]FIG. 6 is a perspective view of another conceptual motor assemblycontemplated by this invention;

[0012]FIG. 7 is an exploded view of the conceptual motor assemblyillustrated in FIG. 6;

[0013]FIG. 8 is a cross-sectional view of another embodiment of a motorassembly with an embodiment of the spray cooling system contemplated bythis invention;

[0014]FIG. 9 is a cross-sectional schematic view of an embodiment of amotor with a spray cooling system contemplated by this invention;

[0015]FIG. 10 is detail a-a from FIG. 9 illustrating a segmentedelectronics assembly encapsulated within the motor system; and

[0016]FIG. 11 is a cross-sectional schematic view of an embodiment of amotor with a spray cooling system contemplated by this invention,wherein the pump is retained external to traditional motor housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Many of the fastening, connection, manufacturing and other meansand components utilized in this invention are widely known and used inthe field of the invention described, and their exact nature or type isnot necessary for an understanding and use of the invention by a personskilled in the art or science; therefore, they will not be discussed insignificant detail. Furthermore, the various components shown ordescribed herein for any specific application of this invention can bevaried or altered as anticipated by this invention and the practice of aspecific application or embodiment of any element may already be widelyknown or used in the art or by persons skilled in the art or science;therefore, each will not be discussed in significant detail.

[0018] The terms “a”, “an”, and “the” as used in the claims herein areused in conformance with long-standing claim drafting practice and notin a limiting way. Unless specifically set forth herein, the terms “a”,“an”, and “the” are not limited to one of such elements, but insteadmean “at least one”.

[0019] Contained in the Appendix hereto is a provisional application anddisclosure, which is hereby incorporated herein by this reference asthough set forth fully herein.

[0020] While there are several types of motors with which this inventionmay be used, some may be more preferred than others. One example of apreferred type of motor for this invention is a variable or switchedreluctance motor “VSR” or “SRM”. It will be appreciated by those ofordinary skill in the art that there are numerous different types ofmotors with which the spray coolant system may be utilized to provideenhanced thermal and other characteristics of the motor, with no one inparticular being required to practice this invention. Examples ofdifferent types of motors are, without limitation, variable switchedreluctance motors, induction motors, synchronous motors, DC (directcurrent) and AC (alternating current) commutator motors, reluctancemotors, hysteresis motors, and others. Motors of all types and kinds arewell known by those of ordinary skill in the art and will not thereforebe discussed in significant detail herein.

[0021] While it is preferred that the motor electronic controls andspray system be entirely contained within or integrated within the motorhousing, this is not necessary to practice this invention. Thisinvention applies to spray cooling systems for motors in which some orall of the components may be outside the motor housing, such as the pumpfor instance.

[0022]FIG. 1 is a perspective view of a conceptual motor system 100which includes a spray cooling system, FIG. 1 illustrating motor system100, motor base 101, first support 112, second support 113, rotor 106,stator 105, output or shaft bearing 104, drive gear 103, output shaftaperture 110 and output shaft aperture seal 111. The output shaftaperture seal 111 may be any one of a number of types, including withoutlimitation, sliding elastomeric seals, ferro-fluidic seals or any one ofa number of others, all within the contemplation of this invention.

[0023]FIG. 1 illustrates a spray assembly 107 at a first end of motorassembly 100 with the output shaft aperture 110 being at the second endof the motor assembly. Although in the example illustrated in FIG. 1 thespray assembly 107 is located at a first end of the motor system 100 andopposite the output end of the motor system, it is not required to be inany particular location as will be appreciated by those of ordinaryskill in the art. While not necessary to practice this invention, it ispreferred that the spray nozzles be located at an end of the motorsystem.

[0024] There are different types of coolant atomizers which may beutilized in the practice of this invention and the invention is notlimited to any one type or kind. The preferable atomizer is a pressureswirl atomizer such as that provided in U.S. Pat. No. 5,220,804,Inventor Tilton, issued Jun. 22, 1993, and U.S. Pat. No. 6,016,969,Inventor Tilton, issued Jan. 25, 2000, both of which are incorporatedherein by this reference.

[0025] It is also preferred that the spray coolant be an evaporativespray coolant (preferably a dielectric) which disburses a thin liquidfilm over various pre-determined motor assembly or system componentswithin the motor housing. The evaporative spray coolant may remove heatfrom said components during evaporation and other phases. The motorsystem also preferably provides, either inherently or mechanically,condensation capabilities to condense any evaporated or vaporized spraycoolant for further spraying and cooling operations.

[0026] There are numerous types of coolants that may be utilized inembodiments of this invention, with no one in particular being requiredto practice this invention. For instance, a preferred coolant is aFluorinert (R) type of coolant, such as FC72 or FC-82 fluid manufacturedby and/or available through the 3M Company.

[0027]FIG. 2 illustrates an exemplary or conceptual 8 pole rotor 120which may rotate about rotor axis 121 and further illustrates statorpole/winding 122 positioned relative to the rotor.

[0028]FIG. 3 is an end elevation view of detail 3 from FIG. 2,illustrating stator pole/winding 122. The aperture 123 in statorpole/winding 122 is not a normal component to the stator pole/winding122 but instead may be utilized in testing to provide additional heat tofurther appraise the thermal transfer characteristics of a system duringtesting. There is no one particular type of stator 122 which must beutilized by any embodiment of this invention, as any one of the numberof types of stators may be used in the practice of the invention.

[0029]FIG. 4 illustrates one embodiment of a spray assembly 140 whichmay be utilized in this invention, illustrating a plurality of nozzleareas 141 which would each include a plurality of nozzle apertures 142.Spray assembly aperture 144 allows for typical motor components to beplaced there-through.

[0030] The spray assembly 140 may include, define and/or comprise apressurized fluid intake and/or distribution manifold to receive acoolant from a pump assembly and through fluid communication with thenozzle apertures 142 provide the required coolant under pressure to thenozzle apertures 142 for spraying. While it is preferred to utilize aspray assembly 140 or spray manifold in this invention, it is notnecessary as individual coolant conduits and widely placed spray nozzlesmay also be utilized. One of the other examples may be the fluidconduits illustrated in FIG. 11.

[0031]FIG. 5 shows a partial schematic representation of one of thenumerous orientations of the spray assembly 140 with nozzle areas 141and nozzle apertures 142 relative to exemplary stator pole/windings 122and rotor pole 120. The positioning of nozzle apertures 142 betweenstator poles 122 provides one example of an efficient atomizationpattern for distribution of the coolant through the statorpoles/windings 122. The positioning of the nozzle apertures 142 as shownin FIG. 5 also provides spray cooling to rotor 120 and the poles ofrotor 120 through one or more of the nozzle apertures 142. In practiceand various applications, certain nozzle apertures may be primarilydirected to the stator and some may be primarily directed to the rotor,with still others being primarily directed to provide spray coolant toboth the stator and the rotor. Again, no particular configuration isrequired to practice this invention.

[0032]FIG. 6 represents one exemplary embodiment of a motor assembly 160which utilizes a spray coolant system. FIG. 6 illustrates motor assembly160, motor housing 161, first support 162, second support 163, outputshaft 164 rotatably mounted within first support 162, motor base 165,spray assembly 167 at the second end of motor assembly 160, the same endas the output shaft 164. Again, no particular motor assembly,configuration or components are required for motor cooling systemscontemplated by this invention.

[0033]FIG. 7 is a perspective exploded view of the motor assembly 160shown in FIG. 6, illustrating rotor 180, first support 162, secondsupport 163, spray assembly 167, stator 181, bearing 182, output shaft164, and base 165. The rotor 180 is an 8-pole rotor, although not allrotor poles are shown in FIG. 7.

[0034]FIG. 8 is an exemplary cross-sectional view of another embodimentof a motor system 190 contemplated by this invention, illustrating motorsystem 190, motor housing 191, condensing fins 192, cooling fins 193,stator windings 200 within stator 195, stator cooling atomizers ornozzles 201, rotor cooling atomizers or nozzles 202, rotor 194 withrotor filler 197 and output shaft aperture 198. It will be noted thatalthough a cooling atomizer may be referred to herein as a stator or arotor cooling nozzle, either may provide cooling to either or both ofthe stator and/or the rotor.

[0035]FIG. 8 is shown with a rotor 194 which includes spaced apart poleswith a dielectric polymer filler 197 inserted between the spaced apartpoles, thereby creating a continuous outer surface. The filler 197 neednot be of any particular material and reduces the windage losses duringthe rotation of the rotor 194.

[0036] Although within motor housing 191, breather aperture 205 andreceiver aperture 206 are shown but need not be within or integral withmotor housing 191. The breather aperture 205 is provided because it isdifficult to keep all air outside the system and air may be drawn intothe motor housing, causing non-condensables to form as a result of thewinding and electronic component out-gassing. If the non-condensablesare allowed to accumulate, these gases may have a negative effect on thecooling system performance. Therefore, one or more breathers 205 may beprovided, such as a molecular sieve, to assist in expelling the gases.The sieve for example may consist of a porous ceramic structure which isimpervious to fluid coolant molecules but which allows smaller moleculessuch as air to pass freely therethrough.

[0037] A check valve may also be required to prevent air infiltrationduring low ambient conditions. Although an example of a breather isdescribed herein, those of ordinary skill in the art will appreciatethat no particular type of breather is required, but any one of a numberof different types of materials and systems may be utilized to, amongother functions, help remove or minimize non-condensables within themotor housing system.

[0038] The receiver 206 shown may be provided to buffer the effects ofthe widely varying operating conditions, in addition to providing liquidvolume to compensate for leakages in the motor cooling system. Areceiver volume may be a lengthwise cylinder contained as an integralpart of the motor casing and may be actively controlled to prevent itsdischarge during off periods or low ambient conditions, as well as toprovide cooling assistance to start-up electronics.

[0039] While a condenser may preferably be utilized by embodiments ofthe motor cooling system contemplated by this invention, it is notrequired to practice this invention.

[0040] The condenser may be designed to trap liquid at the pump sectionduring off periods to avoid thermally stressing the electronics uponstartup. Vapor bypassing is preferably prevented during all phases ofoperation, including the absence of gravity, under inverted positionsand under transient conditions, as may be required by some applicationsof this invention. While it is preferable that the condenser be anintegral part of the motor system and/or motor housing, thisconfiguration is not necessary to practice this invention.

[0041] A shaft seal is also provided and is important to the viabilityof liquid cooled motors in most applications. It will be important tohold leakage of the fluid coolant to a minimum and oftentimes shaftseals are subject to the particular pressure imposed within the motorhousing. Sliding elastomeric, ferro-fluidic and other types of seals maybe utilized within the contemplation of this invention.

[0042] The condensing fins 193 provide surface area for cooling ofatomized or vaporized coolant in the condensing channels 192 which maybe in the motor housing, and should improve the overall performance ofthe motor cooling system. A coolant such as that manufactured by the 3-MCompany referred to as Fluid FC-87 is an ozone safe dielectricperfluorocarbon which works well in some embodiments of this invention.A thin liquid film evaporation of spray coolant appears to be relativelyefficient way of cooling electric motors, and amenable to the small gapsthat exist between components of typical electric motors.

[0043] Only a small temperature rise may be required in order tovaporize and/or evaporate and condense the coolant with a minimumquantity of liquid present in the motor, according to the coolant usedand the temperature at which it operates. Minimizing the liquid quantityof coolant (compared to full immersion of the interior of the motorhousing) reduces pumping power requirements, the viscous losses and thepotential for hydraulic damage. This invention is designed to deliveronly sufficient coolant to maintain a thin film on the cooled surfaceswith a minimum of carryover, it is preferred not to wholly fill themotor housing with coolant. The preferred coolant liquid film to beplaced on internal components may be much thinner than thestator-to-rotor gap and the clearances between adjacent stator windings,which allows better distribution of the coolant throughout thecomponents to be cooled.

[0044] Another aspect which may be utilized in some embodiments of thisinvention is to apply the spray cooling to motor electronics or motorcontrols which may be located within the sealed motor housing or case(as illustrated in FIGS. 10 and 11). This may effectively reduce thesize and weight of the motor controls and electronics assembliesrequired therefor, just as the spray cooling and thermal effects thereofmay allow for the reduced size of motors.

[0045] It is preferable to utilize miniature pressure-swirl atomizers toatomize the coolant and spray it on the internal motor components to becooled. This system, in providing electronics, the motor electronics, orcontrol within the integrated motor housing, may also utilize over-sprayand coolant vapor to cool the motor controls, although atomizers andnozzle orifices may be provided and directed toward the motor controlsalso, depending on the application or embodiment of this invention.

[0046] The motor control electronics may partially or entirely cooled byliquid carryover in entrained droplets which may be transported to thecondenser region by the vapor within the motor housing.

[0047] Condensation channels may be provided within the motor case aslongitudinal grooves on the interior radius or interior surface of themotor housing, forming closed channels within the stator in place,forming closed channels with the stator. Vapor and liquid exiting thestator and rotor cavities immediately enter the condensation channelswhich are in fluid or operative communication with the motor cavity atthe exit end only. At the opposite end, the channels terminate directlyinto the fluid pump suction manifold which is utilized to continuouslyprovide fluid to the atomizers.

[0048] The low pressure receiver 206 in the motor housing illustrated inFIG. 8 may have one or more of the following 3 functions: (a) providingmakeup and recharge capability for any leakages in the system; (b)controlling system pressure; and (c) assisting during start-up byreducing or eliminating a delay in the delivery of coolant.

[0049]FIG. 8 further illustrates condensing channels 207 through whichcoolant of all phases may flow to provide a condensing function beforethe coolant is provided to the coolant pump (not shown in FIG. 8).

[0050]FIG. 9 is a schematic representation of a cooling systemconfiguration contemplated by an embodiment of this invention,illustrating motor assembly 230, output shaft 231, output shaft bearings232, motor housing 237, stator 234 and rotor 233. FIG. 9 furtherillustrates condensing channel 236 which is the same as condensingchannel 207 in FIG. 8, and the flow of fluid there-through as depictedby arrows 245.

[0051] Coolant filter 235 provides filtering to the coolant beingsprayed on the interim components and cooling channel 240 providesreturn flow. The coolant spray 242 may be 2-phase flow leaving the gapand/or cooling channel/conduit 240 through which the coolant iscirculated for cooling. The spray 242 may be directed toward segmentedelectronics assemblies 243 to provide an integrated electronics package,which includes spray cooling of the electronics, within the integratedmotor housing.

[0052] Segmented electronics assemblies 243 are shown and detail 10 isshown in FIG. 10, which is described more fully below. Coolant pump 250is illustrated with suction manifold 239 through which fluid iscommunicated, received and communicated to the coolant pump 250. Thecoolant received in suction manifold 239 may be received for instancefrom condensing channel 236 through apertures there-between. Coolantsbeing atomized for cooling of the rotor and/or stator may pass through acoolant filter such as coolant filter 235. FIG. 9 further illustratesend windings 260 to stator 234 and terminations 238.

[0053] The depiction of item 243 may also include power switchingcontrols to control and accomplish the switching of the electricitythrough the motor, all of which is well known in the art. An embodimentof this invention includes spray cooling the power switching controlswithin the motor housing.

[0054]FIG. 10 illustrates detail 10 from FIG. 9 and shows the segmentedelectronics assembly receiving 2-phase flow which would be providedthrough cooling channel 240 (as shown in FIG. 9). The motor controls orpower device 270 is encapsulated within electronics assembly 243 with anEMI shield/power insertion/hermetic barrier 271 provided.

[0055]FIG. 11 is a cross-sectional schematic view of an embodiment of amotor with a spray cooling system contemplated by this invention,wherein the pump is retained external to traditional motor housing. FIG.11 illustrates many of the same items or components as shown in FIG. 10,which have been similarly numbered, and which will therefore not berepeated here. FIG. 11 does further illustrate pump 276 external tomotor housing 237, pump enclosure 279, pump outlet conduit 278, atomizeror nozzle assemblies 258 (may also be referred to as spray headers) andpump suction or inlet conduit 277.

[0056] This invention may also be practiced with some components such asthe coolant pump 276 being mounted external to the motor housing 237.Suction header 259 (which is preferably in a ring configuration) is alsoshown.

[0057] Spray cooled motor systems as disclosed herein may be utilized inmost or all applications in which motors are desired and/or used,including without limitation, electric vehicles, industrial uses ofmotors, aircraft, and others.

[0058] As will be appreciated by those of reasonable skill in the art,there are numerous embodiments to this invention, and variations ofelements and components which may be used, all within the scope of thisinvention.

[0059] One embodiment of this invention for example is a spray cooledmotor with a motor housing with an interior and an exterior, a statormounted within the interior of the motor housing, a rotor mounted withinthe interior of the motor housing, a coil winding mounted within theinterior of the motor housing, a plurality of atomizers configured tospray a coolant on at least one of the stator and the rotor, a coolantpump in fluid communication with the plurality of atomizers; and anoutput shaft extending through an output shaft aperture from theinterior to the exterior of the motor housing.

[0060] Further embodiments of the above may be: wherein the motor is avariable switched reluctance motor; wherein the output shaft aperture issealed with the motor housing such that the coolant is contained withinthe interior of the motor housing; wherein the output shaft aperture issealed with the motor housing with a sliding elastomeric seal; and/orwherein the output shaft aperture is sealed with the motor housing witha ferro-fluidic seal; wherein the coolant pump is mounted within themotor housing.

[0061] In another embodiment, a spray cooled motor as recited above isprovided, but which additionally may include heat transfer fins on theexterior of the motor housing, and/or a condensation conduit adjacentthe motor housing such that vaporized coolant passing through thecondensation conduit is condensed.

[0062] Still further embodiments of the above may be a spray cooledmotor as recited above, and further including: motor controls mountedwithin the motor housing; and a plurality of control atomizersconfigured to spray coolant on the motor controls.

[0063] A still further embodiment of this invention is an electric motorvehicle with at least one spray cooled motor system contained thereon.

[0064] In compliance with the statute, the invention has been describedin language more or less specific as to structural and methodicalfeatures. It is to be understood, however, that the invention is notlimited to the specific features shown and described, since the meansherein disclosed comprise preferred forms of putting the invention intoeffect. The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

I/We claim:
 1. A spray cooled motor comprising: a motor housing with aninterior and an exterior; a stator mounted within the interior of themotor housing; a rotor mounted within the interior of the motor housing;a coil winding mounted within the interior of the motor housing; aplurality of atomizers configured to spray a coolant on at least one ofthe stator and the rotor; and a coolant pump in fluid communication withthe plurality of atomizers.
 2. A spray cooled motor as recited in claim1, and wherein the motor is a variable switched reluctance motor.
 3. Aspray cooled motor as recited in claim 1, and wherein the output shaftaperture is sealed with the motor housing such that the coolant iscontained within the interior of the motor housing.
 4. A spray cooledmotor as recited in claim 3, and further comprising an output shaftextending through an output shaft aperture from the interior to theexterior of the motor housing, and wherein the output shaft aperture issealed with the motor housing with a sliding elastomeric seal.
 5. Aspray cooled motor as recited in claim 3, and further comprising anoutput shaft extending through an output shaft aperture from theinterior to the exterior of the motor housing, and wherein the outputshaft aperture is sealed with the motor housing with a ferro-fluidicseal.
 6. A spray cooled motor as recited in claim 1, and furthercomprising: motor controls mounted within the motor housing; and aplurality of control atomizers configured to spray coolant on the motorcontrols.
 7. A spray cooled motor as recited in claim 1, and wherein thecoolant pump is mounted within the motor housing.
 8. A spray cooledmotor as recited in claim 1, and further comprising heat transfer finson the exterior of the motor housing.
 9. A spray cooled motor as recitedin claim 1, and further comprising: heat transfer fins on the exteriorof the motor housing; and a condensation conduit adjacent the motorhousing such that vaporized coolant passing through the condensationconduit is condensed.
 10. A spray cooled motor as recited in claim 1,and further comprising an output shaft extending through an output shaftaperture from the interior to the exterior of the motor housing.
 11. Aspray cooled motor as recited in claim 1, and further wherein the motoris electronically coupled to an output on the exterior of the motorhousing.
 12. A spray cooled motor as recited in claim 1, and furtherwherein the rotor includes spaced apart poles with a polymer fillerinserted between the spaced apart poles, thereby creating a continuousouter surface.
 13. A spray cooled motor as recited in claim 1, andfurther comprising: motor power switching controls mounted within themotor housing; and a plurality of control atomizers configured to spraycoolant on the motor power switching controls.